REMOVAL OF ARSENIC FROM DRINKING WATER WITH ENHANCED HYBRID
ALUMINAS AND COMPOSITE METAL OXIDE PARTICLES
Bryan E. Kepner†, John Spots†, Eric A. Mintz‡, Jeffrey, E. Cortopassi‡,
Paul Abrahams‡, Carlton E. Gray‡, Santosh Matur*
†
Apyron Technologies, Inc., 4030-F Pleasantdale Rd., Atlanta Georgia, 30340, U.S.A.; Department of
Chemistry, Clark Atlanta University, 223 James P. Brawley Dr. S. W., Atlanta, GA 30314, U.S.A.;
*RPM Marketing Pvt. Ltd., C-23 Friends Colony, New Delhi 110065 India.
INTRODUCTION
Arsenic contamination of drinking water is a world-wide problem which has hit the West Bengal
region of India particularly hard.1 Long term exposure to arsenic via drinking water leads to a wide range
of health problems including: skin cancer, gangrene of the limbs, vascular diseases, conjunctivitis, central
nervous system damage and hyperkeratosis.2 Methods such as coagulation3 and reverse osmosis4 have
been shown to be effective for the removal of arsenic from water. However, these methods require
considerable infrastructure and are expensive to operate, thus making them impractical for small
community scale water treatment systems. As a large number of people in West Bengal obtain their
water from small wells, as opposed to from large municipal water plants, it is necessary to develop
technology that can be implemented on a small scale to remove arsenic from drinking water as it is
extracted from the well. Several investigators have reported adsorption methods for the removal of
arsenic from drinking water5, however there is still a need to develop effective field deployable adsorbents
and delivery systems. We have developed enhanced hybrid aluminas and alumina-metal oxide composite
particles that have proven effective for the removal of arsenic from water.
METHODOLOGY
Enhanced hybrid aluminas (EHAs) were prepared by heating beohmite to 400o C for 1 hr followed
by treatment with 0.5 % acetic acid for 15 min (PBHK). [need data on AQA]. The alumina samples
were then dried but not calcined.6 Alumina-metal oxide composite particles (Al-MOC) were prepared by
binding EHAs and metal oxides utilizing a proprietary colloidal alumina binder system.7 Head to head
comparison of the different media for the removal of arsenic from water was carried out. Approximately
one gram samples of enhanced hybrid alumina or alumina-metal oxide composite particle were tumbled
with 495 mL of 50 ppm arsenic solutions (a large excess of arsenic) for 24 hours. The solutions were
filtered and subjected to inductively coupled plasma/mass spectroscopy (ICP/MS) to determine the
arsenic concentration. The arsenic solutions were prepared by dissolving AsO3 in 1-4 % nitric acid. The
results of these experiments are given in Table 1.
The removal of arsenic as a function of pH was examined for an enhanced hybrid alumina
(PBHK), an alumina-alumina composite particle (82AHC), an alumina-manganese oxide composite
particle (1F97SLIN), and an alumina-iron oxide composite particles 2F97SLIN. In a manner similar to
that above approximately one gram samples of EHA or alumina-metal oxide particle were tumbled with
495 mL of 50 ppm arsenic solutions (a large excess of arsenic) which had been adjusted to approximately
pH 4.2, 7, 9, 11 or 13.3, to allow head to head comparison of the different media for the removal of
arsenic from water as a function of pH. The arsenic solutions were prepared by dissolving AsO3 in 1-4 %
nitric acid followed by pH adjustment with NaOH. The results are shown in Figure 1. At very low pH
1F97SLIN partially dissolves, and reacts with the arsenic, leading to an anomalous high adsorption result.
At very high pH the alumina partially dissolves, and reacts with the arsenic, leading to an anomalous high
adsorption result. In the drinking water pH range all four of these adsorbents exhibit good arsenic
removal when no other contaminants are present.
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Table 1: Head-to-Head Comparisons of Selected Enhanced Hybrid Aluminas and Alumina-Metal
Oxide Composite Particles For the Adsorption of Arsenic
Sample
AQA
g’s
sorbent
1.026
[As]i
(ppm)
50
[As]f
(ppm)
38
Volume As absorbed % absorbed
(mL)
(g/kg)
495
5.79
24.0
BW
PBHK
1.004
0.985
50
50
41.6
35.7
495
495
4.14
7.19
16.8
28.6
82AHC
1F97SLIN
0.967
1.059
50
50
35.8
3.01
495
495
7.27
21.96
28.4
94
2F97SLIN
3F97SLIN
0.981
1.044
50
50
36.5
16.2
495
495
6.81
16.03
27.0
67.6
4F97SLIN
1.031
50
3.95
495
22.11
92.1
5F97SLIN
1.025
50
3.87
495
22.28
92.3
Particle
Enhanced Hybrid
Alumina (see text)
Base washed AQA
Enhanced Hybrid
Alumina (see text)
Alumina/Alumina
Alumina/Manganese
Oxide
Alumina/Iron Oxide
Alumina/Iron
Oxide/Manganese
Oxide
Alumina/Manganese
Oxide
Alumina/Manganese
Oxide
[As]i = initial arsenic concentration ppm (mg/L). [As]f = final arsenic concentration ppm (mg/L).
Figure 1: Removal of Arsenic (Grams Arsenic/Kg Media) as Vs. pH
25
gAs/Kg
20
15
10
5
0
0
2
4
6
8
10
12
14
16
pH
PBHK
82AHC
1F97SLIN
2F97SLIN
As the alumina manganese oxide composite particle proved most effective for arsenic removal at
pH 7 we further examined the effect of varying the manganese content of the composite on the arsenic
removal capacity. Figure II indicates that increasing the manganese oxide composition above 10 % in the
alumina-manganese oxide composite particle does not increase the arsenic removal capacity of the
composite particle.
2
Effect Of Manganese Oxide Composition On The Arsenic Uptake Capacity Of
Alumina/Manganese Oxide Composite Particles.
Grams Arsenic/Kg
Media
Figure II:
25
20
15
10
5
0
0
10
20
30
40
50
% Maganese Oxide
Water samples were obtained from the Santipur Water Supply (Zone II) at Phatakapra in the
Nadira District in West Bengal and analyzed by ICP-MS to determine the contaminants in the water.
Column 1 in Table II lists the concentrations of ions found with a concentration of greater than 1 ppb.
Based upon the composition of the water obtained from the Santipur water supply, water samples were
prepared that were spiked with Na+, Mg++, Ca++, Fe++, Cu++, Zn++, Cd++ and Pb++ in addition to arsenic
and the pH adjusted to 8.0. An enhanced hybrid alumina (PBHK) and an alumina-manganese oxide
composite particle (1F97SLIN) were tested against these “synthetic” water samples. The PBHK was
found to be less effective than 1F97SLIN in the presence of high concentrations of Na+, Mg++, and Ca++
for the removal of arsenic. Further experiments have established that the alumina-manganese oxide
composites are “self protecting” from the high concentration of Mg++, and Ca++ ions. Many adsorbents
that remove arsenic from otherwise pure water in the laboratory have not fared well in the field because
of the competition of Mg++ and Ca++ and other naturally occurring ions for adsorbent sites that would
otherwise be available for arsenic.
A water sample from the Santipur water supply was then treated in a small column test with
1F97SLIN. The concentration of contaminants in the 15Th bed volume of this test are give columns 2 of
Table II. This and other tests indicate that 1F97SLIN is effective for the removal of arsenic in typical
well water which is high in Mg++ and Ca++ and other naturally occurring ions. Column 2 in Table II also
indicates that the 1F97SLIN is effective for the removal of other harmful metals, such as cadmium,
antimony, lead and uranium, from the well water.
A prototype unit for the removal of arsenic from well water is shown in figure II. Figure III gives
the internal details of this unit. A field test is currently in progress in Phatakapra in the Nadira District in
West Bengal to further test the efficacy of alumina-manganese oxide composites for the removal of
arsenic from well water on site. Table III gives the initial results of this field test.
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Table II: Well Water Before and After Treatment With 1F97SLIN.
Column
Element
Li
B
Na
Mg
Ca
Fe
Cu
Zn
Ga
Ge
As
Cd
Sb
Ba
Pb
U
pH
1
2
Untreated Well Water 1F97SLIN Treated Well
Water
ppb
ppb
7.01
2.48
22.16
3.88
18650
>1513
48440
8817
7981000
522700
1495
11.62
177
0.00
50.48
0.00
0.02
0.02
33.29
0.02
176.5
0.00
1.27
0.13
47.56
0.26
7.93
0.01
2.18
0.00
1.13
0.01
7.7
7.70
Figure II: Prototype Unit For The Removal Of Arsenic From Well Water
Hand Pump
Clamp
Blue Flex Hose
Apyron
Arsenic
Removal
System
4
System engineered for a maximum
flow rate of 2 gal/min. (7.6 L/min)
Figure III: Internal Details Of Prototype Field Unit.
FLEX LINE
(Attach to hand
pump)
BAND CLAMP
FLANGE
TOP COVER
DISTRIBUTION
DISK
DIFFUSER
SCREEN
BULKHEAD
FITTING
APYRON
MEDIA
DIFFUSER
PLATE
ELBOW
FAUCET
INNER
CONTAINER
FRIT
SCREEN
Arrows
Indicate Flow
SUPPORT
OUTER
CONTAINER
5
ACKNOWLEDGMENT
The Georgia Research Alliance for the acquisition of the Perkin-Elmer Elan 5000 ICP-MS System
used for the arsenic analysis for this project.
1
2
3
4
5
6
7
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Moskovitz, M. L. and Kepner, B. E. U. S. patent pending 95-426981.
Moskovitz, M. L. and Kepner, B. E. U. S. patent pending 94-351600.
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